Crankcase scavenging pump for refrigeration compressor



Oct. 1, 1968 s. A. PARKER 3,403,845.

CRANKCASE SCVENGING PUMP FOR REFRIGERATION COMPRESSOR Filed May 2.3, 1966 2 Sheets-Sheet 2 C1 F-g. 5

Pig-3 @26 SEI" /09 /0/' /08 W INVENTOR.

MMM

Arron/vers S/DNE Y A. PARKER.

United States Patent O 3,403,846 CRANKCASE SCAVENGING PUMP FOR REFRIGERATION CGMPRESSR Sidney A. Parker, Fort Worth, Tex., assignor to Lennox Industries, Inc., a corporation of Iowa Filed May 23, 1966, Ser. No. 552,201 11 Claims. (Cl. 230-206) ABSTRACT F THE DISCLOSURE A refrigerant compressor with pump means in the upright crankshaft thereof communicating with a passage in the crankcase for removing lubricant above a predetermined level from the crankcase. A check valve may be provided in the outlet of the passage to prevent return of lubricant from the sump to the crankcase during the yoff cycle. In a modification, a conduit is connected at one end with the passage in the crankcase, with the other end being above the maximum lubricant level in the sump formed between the compression mechanism and the outer casing of the compressor.

This invention relates to .a hermeticv refrigerant compressor and, more particularly, to an improved compressor of the type having a vertical crankshaft and including means on the crankshaft for reducing the oil level in the crankcase during operation below the operating mechanism to reduce the energy losses and thereby reduce the watts input to the compressor motor.

The trend in the refrigeration industry is toward compact refrigerant compressors driven at relatively high speeds. In one type compressor design, the vertically extending -crankshaft is jou-rnaled in compression means resiliently supported in a sealed outer case. The compression means is defined in part by a crankcase. The drive motor for the crank-shaft is located above the compression mechanism in the crankcase.

The hermetic compressor includes a welded shell or outer casing, the lower portion of which defines an oil sump. When the compresso-r is inoperative, the crankcase is partially submerged in the sump and oil is within the crankcase above the level of the operating mechanism therein. A relatively large supply of oil is desirable to reduce the adverse effects caused by miscibility of refrigerant .and oil. However, it is desirable during operation of the compressor to reduce the oil level in the crankcase below the pistons and the fiywheel portion on the lower end of the drive shaft to minimize operational losses due to frictional drag of the drive shaft and parts of the operating mechanism in the oil and to decrease the watts input to the electric drive mot-or.

In the operation of one present compressor design, disclosed for example in Gerteis Patent 3,008,629, discharge gas bypasses around the pistons, increasing the pressure within the crankcase, which is open to the crankcase only below the normal level of oil or lubricant in the sump. The difference in pressures acting on the oil displaces the oil from within the crankcase. By this construction, there is provided a compact hermetic compressor design, for lubricant is displaced into the annular space defined between an annular sleeve carrying the crankcase and the lower portion of the outer casing.

The above-noted compressor design is dependent upon an imperfect mating of a piston and its sealing rings within a cylinder in the compressor block. With modern fabricating equipment land techniques, there need not be very much leakage of gas between a piston and the wall `of an associated cylinder. If there were only very little leakage, insufficient pressure would be built up in the crankcase to force .the oil or like lubricant through an "ice opening therein below the level of oil in the sump. Further, under low load conditions, there would be little bypass or blowby of discharge gas about the pistons of the compression mechanism and thus, there would be insuffiient pressure in the crankcase to displace lubricant thererom.

It is desired that oil be removed from within the crankcase during operation in order to minimize interference with the pumping action and to increase the operating efficiency of the electric drive motor.

Further, Ias compressors of this type are built in larger sizes and cylinder unloading means are utilized, there would be insufiicient bypass of discharge gases about the pistons during unloading conditions to pressurize the crankcase.

An object of the present invention is to provide a hermetic refrigerant compressor having compression mechanism within which is defined a crankcase at least partially filled with lubricant when the compressor is inoperative with improved means for displacing lubricant from the crankcase during operation to maintain the lubricant below the level of the operating mechanism.

Another object of this invention is to provide a hermetic refrigerant compressor of the type including a vertically disposed crankshaft having a counterweight adjacent the lower end journaled in a compression block defining a crankcase, with improved means for displacing lubricant from the crankcase during operation to maintain the lubricant level below the counterweight to increase the operating efficiency of the compressor and reduce the electrical input to the electric drive motor, the displacing means including a pump in the crankshaft which cooperates with passage means in the compressor block that communicates the interior of the crankcase with the lubricant sump defined between the compressor bl-ock and the outer casing of the refrigerant compressor.

The specific structural details of the invention and their mode of opera-tion will be made most manifest and clearly pointed out in full, concise and exact terms in conjunction with the accompanying drawing, wherein:

FIG. 1 is a cross-sectional view of a hermetic refrigerant compressor embodying the present invention:

FIG. 2 is an enlarged detail view of the pump means in the flywheel portion of the crankshaft for removing lubricant from the crankcase during operation.

FIG. 3 is a bottom view of the crankcase illustrating the location of passage means in the crankcase for returning lubricant to the sump;

FIG. 4 is an enlarged detail view illustrating ya check valve means associated with an oil relief hole in the crank case;

FIG. 5 is a plan view of a check valve that may be used in the check valve means of FIG. 4;

FIG. 6 is a plan view of a modified counterweight that can be detachably affixed to a crankshaft, such counterweight being provided with a grooved passage in the exterior end surface thereof; and

FIG. 7 is a cross section of the modified counterweight taken generally along line 7-7 of FIG. 6.

Referring to the drawing, there is illustrated in FIG. l a refrigerant compressor 10 embodying the present invention. The compressor comprises a gas-tight housing including an upper shell 12 and a lower shell 13 integrally joined to one another, as for example, by welding. A plurality of legs 14 may be welded to the lower shell of the compressor for supporting the compressor in an upright position.

Resiliently supported within the outer housing or casing of the compressor 10 is a compression mechanism that includes a compressor block 15 carrying annular sleeve means 20 thereon. The compressor block 15 comprises a motor flange portion 16 and a cylindrical crankcase flange portion 17 divided by partition or wall means 18. Surrounding the lower portion 17 of the crankcase in spaced relationship to the lower shell 13 of the outer casing is annular sleeve 20. Formed integrally on the top of the annular sleeve 20' is an out-turned, ring-like flange 21. An annular member 22 having a transversely disposed lower ring-like flange 23 is affixed to the lower shell 13. A plurality of resilient spring means 24 are provided between the flange members 21 and 23 for resiliently supporting the crankcase within the outer housing.

Provided within the crankcase 15 are a plurality of cylinders 26. Although a four-cylinder compressor is illustrated, it will be understood by those versed in the art that any desired number of cylinders may be employed. Cylinder sleeves or liners 27 are provided in each of the cylinders 26 and a suitable piston 28 is adapted to reciprocate within each of the cylinder liners Z7. Each piston 28 is operatively connected to the eccentric portion 29 of the vertically disposed crankshaft 30, which is journaled in spaced bearings within the crankcase 15. The means for operatively connecting the piston 28 to the crankshaft 30 include a connecting rod 32, which is affixed at one end to the eccentric portion 29 of crankshaft or drive shaft 30 and at the other end to a wrist pin 34 carried in piston 28.

Closing the end of each cylindercavity is a valve assembly 36. Such valve assembly may comprise a discharge valve unit 37, a suction valve plate 38 and a suction Valve or reed member 39. Each valve assembly is operative in a conventional manner.

The valve assemblies 36 are each held in place in the end of a cylinder by means including a cap 40` retained in position by a spring 42 for example, a Belleville spring and a retaining ring 44.

Provided on the crankcase are a pair of annular circular sealing flanges 46 and 47. These flanges are provided with recesses within which are disposed O-rings 48 and 49 for sealing between the annular sleeve 20 and the respective flanges 46 and 47. Defined between the exterior of the crankcase and the annular shell 20 is a space 50 into which discharge gases are passed from the cylinders 26 after compression The discharge gases pass from the annular chamber 50 through a ydischarge conduit 51 to the conduit 53 for discharge from the compressor to the condenser of the refrigerating system in a known manner. The annular space t) is provided with a plurality of cavities t-o impart a muflling effect to the discharge gases which are discharged from the cylinders into the space 50 prior to discharge from the compressor.

Suction gas enters the casing of the compressor via suction fitting 52 in a conventional manner and passes through a labyrinth or space 54 defined between flange 23 on sleeve member 22 and flange 21 on sleeve 20 into the top of the outer housing. The suction gas then passes through opening 56 in the motor cap or end cap 57 aflixed to the motor flange portion 16 of the compressor block and kdown over the electric motor 58, thereby cooling the motor. The suction gas passes through the motor compartment into the valve assemblies 36 via passage means comprising an opening 59 in the partition 18 and an opening 60 in the discharge valve assembly 37. Thus, it is seen that the space between the hermetic casing and the compression means is substantially at suction pressure.

The motor 58 comprises a stator 62 which is mounted within the motor flange portion 16 of the compressor block or crankcase 15. The stator 62 is inductively connected to the rotor 64 which is afllxed onto the upper portion 65 of the crankshaft 30. The rotor is suitably connected to portion 65 of drive shaft 30, as for example, by means including key 67.

The crankshaft 30 may be journaled within a lower bearing 68 which is mounted in the lower bearing head 70. The lower bearing head 70 is maintained in position by a suitable wedge lock spring or retaining spring 72 seated within an annular groove in the compressor block 15. Also provided in the lower bearing head 70 is a thrust bearing 73, which has a central opening 74 defined therethrough. Located in the lower portion 75 of the crankshaft 30 adjacent the counterweight portion 76 is an axial hole 77 that is coaxial with opening 74 in bearing 73. The hole 77 constitutes the eye lof the pump means which are defined within the crankshaft 39 for lubricating the upper and lower crankshaft bearing surfaces and the connecting rod bearing surfaces. Screen 79 suitably affixed to bearing head 70 prevents particles that may be present in the sump from entering the pump means in the crankshaft.

The pump means for lubricating the bearing surfaces are not part of the present invention and reference may be made to copending application Ser. No. 361,126, filed Apr. 20, 1964, for a fuller explanation of the pump means. The pump means comprise a vertically disposed passageway 80 in crankshaft 30 which is offset from the axis of rotation of crankshaft 30 and is communicated with the eye 77 of the pump means by means of a transversely disposed passage 81 for feeding lubricant to the upper bearing means. Passage 81 is open at its ends to lubricate bearing 68. A second vertically disposed passage and a third vertically disposed passage are provided in the crankshaft for supplying lubricant to a plurality of ports 82, 83, 84 and 85 on the surface of the eccentric portion 29 of the crankshaft 3() for lubricating the connecting rod bearing surfaces. The second passage may be vented to the interior of the crankcase to function as a low-pressure pump and the third pump is not vented, thereby functioning as a high-pressure pump.

A heat shield 31 may be provided about the annular sleeve 28 for minimizing heat transfer between the relatively hot discharge gases in the discharge gas muflling chamber 5t) and the relatively cold suction gases in the space between the compression means and the outer casing.

The upper bearing means comprise a first bearing 86 and a second bearing 87 which is spaced from the first bearing to define an annular space 88 therebetween and about the crankshaft 30. The upper end of passage 80 may be vented by upwardly inclined passage 80a and downwardly inclined passage Stlb communicates passage 80 with the space between the bearings 86 and 87.

Means are provided for positively displacing lubricant yfrom the crankcase Iduring operation so as to lower the level of lubricant in the crankcase below the flywheel portion of the crankshaft to thereby minimize frictional drag of the crankshaft in the lubricant and so reduce the power input to the electric motor. The displacing means comprises pump means 90 in the counterweight or flywheel portion 76 of crankshaft 30 and passage means 92 in the crankcase 15 communicating the interior of the crankcase with the sump defined in the bottom of the lower shell or casing 13 between the lower shell and the bottom of the compression means. The pump means 90 (FIGS. 1 and 2) includes a vertically disposed passage 93 having an opening extending to the bottom of the flywheel portion 76 of crankshaft 30 and a radially disposed passage 94 communicating at one end with the passage 93 and at the other end with the groove or skiving 95 in the exterior of the flywheel portion 94. The inlet to passage 93 is in the bottom of the flywheel portion 94 to withdraw lubricant from the crankcase at the level of the bottom of the flywheel portion.

The passage 94 communicates with groove 95, which in turn is adapted to communicate with passages 92 (FIG. 3) in the crankcase 15. The groove 95 is defined by an elongated annular recess in the end surface of the flywheel. Annular ring 96 suitably affixed to the wall 97 within the crankcase cooperates with the shoulder 98 in the crankcase to define annular groove means or recess 99 within which the sector-shaped outer end of the flywheel portion 76 rotates. The tolerances between the exterior surfaces of the outer end of flywheel portion 76 of the crankshaft and the surfaces defining the recess 99 are close so that there is an effective seal defined between the flywheel portion 76 and the recess 99 to confine the flow of lubricant pumped from the interior of the crankcase to the passage means 90, groove 95 and passages 92 for displacing lubricant from the interior of the crankcase to the sump. The upright outer end wall 101 of the flywheel portion 76 is cylindrical and is complementary to the cylindrical internal mating wall of the crankcase. As shown in FIG. 3, there are three passages 92 in the crankcase.

Secured to the crankshaft 30 and rotatable therewith is an annular collar 102 which includes a depending flange 103. The interior surface of the flange 103 cooperates with an annular seal 104 fixed to the upper portion of the partition or wall means 18 which supports the bearing means 86 and 87. By this construction, the passage of lubricant over the bearing 86 into the motor compartment is prevented. Rather, lubricant passing over the top of the bearing 86 or between the bearing 86 and the crankshaft 30 will be returned to the interior of the crankcase via a passage 105 in partition 18. Thus, lubricant is returned from the upper bearing means to the crankcase in a path separate from the suction gas so as to prevent undesirable entrainment of lubricant in the suction gas.

Terminal connector means 108 are provided to connect the motor 58 to a suitable source of electrical power.

The lubricant displacing means include means associated with each of the lubricant relief holes 92 in the crankcase for preventing lubricant from returning to the crankcase when the particular passage 92 is not ejecting oil. The oil return preventing means may include a tube or conduit 120 connected at one end to a hole or passage 92 and at the other end to the chamber between the compression means and the outer casing above the oil level therein (FIG. l). It will be understood that a conduit 120 communicates each hole 92 with the chamber above the maximum oil level in the sump. Fitting 121 secures an end of conduit 120 in passage 92.

Other forms of oil return preventing means are shown in FIGS. 2, 4 and 5. In FIG. 2, there is shown check valve means 121 associated with each passage 92 adjacent the outlet therefrom. Within the body 122 of each check valve means 121, which body is suitably secured in passage 92, is a one-way valve for permitting flow of oil from passage 92 into the sump, but preventing flow of oil in an opposite direction.

In FIGS. 4 and 5, there is shown check valve means 125 comprising :a check valve plate 126 retained in position adjacent the outlet 127 from passage 92 by means of retainer 128. The check valve is movable between a position against the retainer for permitting flow from passage 92 to a position abutting the outlet 127 to prevent oil flow from the sump into the passage 92 when the pressure in the sump is greater than that in the passage.

Referring to FIGS. 6 and 7, there is shown a modified lower counterweight member 76 that is adapted to be remova-bly secured to a crankshaft, as for example, by a bolt 108. The counterweight or flywheel 76' contains pump means 90'that function in essentially the same manner as the pump means 90 shown in FIGS. 1 and 2. For ease of manufacture, passage 93' comprises a hole formed through the counterweight. Passage 93 has inlets both above and below the counterweight. Passage 94 may be defined by a hole bored radially through the counterweight from end surface 101' to the crankshaft opening 110. Positioning set screw 109 closes -an end of the radial hole and passage 94' extends from passage 93' to the periphery of the counterweight. Bolt 108 may be used to properly orient the counterweight on the crankshaft for proper balancing. Groove 95' is formed in cylindrical surface 101', but does not extend to the ends of surface 101. Thus, groove 95' is less in peripheral extent than end surface 101' and is confined within surface 101. Surface 101' is complementary to the interior surface in the crankcase and cooperates therewith in the same way that the surface 101 on counterweight portion 76 cooperates with surface 97 in the device shown in FIGS. 1 and 2.

As best seen in FIG. 6, the flywheel is semi-cylindrical in plan view and extends about The flywheel may be formed as la cylindrical member in plan extending 360. In such case, the scavenging pump means could be formed in the same manner as considered hereinabove. If desired, the annular groove could extend 360 about the end surface of such flywheel. Should the annular groove extend entirely around a cylindrical flywheel or counterweight, there would be a continuous pumping action through the holes 92, and there would be no necessity in such arrangement for the oil return preventing means shown in FIGS. l, 2 and 4. I-t is only where there is not continuous pumping action that there would lbe need for oil return preventing means.

The present compressor design can accommodate a large supply of oil or lubricant to minimize the adverse effects of miscibility of the oil and refrigerant normally used in hermetic refrigerant compressors. The pump means in the counterweight portion of the crankshaft positively maintains the lever of lubricant in the crankcase during operation below the pistons and the flywheel portion of the crankshaft by displacing lubricant from a level at the inlet to the pump means in the flywheel portion of the crankshaft. There is less frictional drag on the crankshaft during operation and the watts input to the electric drive motor is reduced. Further, the means for scavenging and positively displacing lubricant from the interior of the crankcase to the sump are independent of piston design and of load conditions. Such means are also independent of whether or not the compressor is provided with cylinder unloaders. In operation, the pump means provided in the flywheel portion on the lower end of the crankshaft positively displaces lubricant from the interior of the crankcase and returns it to the sump in a path isolated from the suction gases passing over the compressor electric drive motor to the compression mechanism.

While there has been shown and described a particular embodiment of this invention, it will be obvious to those skilled in the art that various changes and modifications may be made therein without departing from the invention and, therefore, it is intended in the appended claims to cover all such changes and modifications as fall within the true spirit and scope of the invention.

What I claim as new, and desire to secure by Letters Patent of the United States, is:

1. In a refrigerant compressor comprising an outer casing, compression means defining a crankcase therein disposed within the outer casing, a vertically extending crankshaft journalcd in said compression means, said crankshaft having a flywheel portion adjacent the lower end thereof, cylinder means in said compression means, a piston reciprocatingly disposed in each cylinder means, means operatively connecting each said piston to said crankshaft, said compression means being partially immersed in lubricant in the sump formed in the lower portion of the outer casing, and pump means in the crankshaft for lubricating the crankshaft bearing surfaces and the connecting means bearing surfaces, the improvement comprising passage means communicating the interior of the crankcase with the sump, and pump means in the crankshaft for removing lubricant above a predetermined level from the crankcase and forcing it through the passage means into the sump so as to maintain the level of lubricant in the crankcase below the predetermined level during operation to increase the operating efficiency of the compressor and reduce the electrical input to the electric drive motor, the pump means being defined in kthe flywheel portion of the crankshaft.

shaft.

3. A refrigerant compressor as in claim 1 wherein the pump means comprise a passage formed in the ywheel portion of the crankshaft and including an inlet communicating with the interior of the crankcase and an outlet for commnicating with the passage means in the compression means during operation for pumping lubricant from the crankcase through the passage into the passage means.

4. A refrigerant compressor as in claim 3 wherein the outer surface of the flywheel portion is disposed closely adjacent to a cylindrical surface of the compression means defining the crankcase for communicating the outlet in the ywheel portion with the opening to the passage means in the compression means during rotation of the crankshaft.

5. A refrigerant compressor as in claim 4 wherein the outlet is defined by annular groove means in the flywheel portion of the crankshaft, and the extremity of the ywheel portion is complementary to the configuration of the inner surface of the compression means, said groove means communicating with the passage means during rotation of the crankshaft whereby lubricant may be pumped from the crankcase by the pump means during operation of the refrigerant compressor.

6. A refrigerant compressor as in claim 5 wherein the groove means are provided in the end surface of the counterweight portion and extend a peripheral distance less than that of the end surface.

7. A refrigerant compressor as in claim 1 wherein means are connected to said passage means for preventing return of lubricant from the sump to the crankcase through said passage means.

8. A refrigerant compressor as in claim 7 wherein said lubricant return preventing means includes a check valve.

9. A refrigerant compressor as in claim 1 wherein a conduit connects at one end to the crankcase in communication with said passage means, the other end of said conduit being disposed above the maximum lubricant level in said sump.

10. A refrigerant compressor comprising an outer casing, compression means defining a crankcase therein disposed wthin the outer casing, a vertically extending crankshaft journaled in said compression means, said crankshaft having a flywheel portion adjacent the lower end thereof, cylinder means in said compression means, a piston reciprocatingly disposed in each cylinder means, means operatively connecting each said piston to said crankshaft, said compression means being partially irnmersed in lubricant in the sump formed in the lower portion of the outer casing and pump means in the crankshaft for lubricating the crankshaft bearing surfaces and the connecting means bearing surfaces, the improvement comprising passage means communicating the interior of the crankcase with the sump, and pump means in `the crankshaft for removing lubricant above a predetermined level from the crankcase and forcing it through the passage means into the sump so as to maintain the level of lubricant in the crankcase below the predetermined level during operation to increase the operating eiciency of the compressor and reduce the electrical input to the electric drive motor, the pump means comprising an upright passage communicated with the bottom surface of the flywheel portion of the crankshaft and a radially extending passage communicated at one end With the upright passage and at the other end with the end surface of the flywheel portion.

11. A refrigerant compressor as in claim 10 wherein the end surface of the flywheel portion is provided with an elongated groove, said groove cooperating with the passage means in the crankcase during rotation of the crankshaft.

References Cited UNITED STATES PATENTS 3,008,628 11/1961 Gerteis '230--206 XR 1/1966 Parker 230-206 

